(1) Field of the Invention
This invention relates to varnish compositions used to make laminates and prepregs that are then used to manufacture printed circuit boards. This invention also is directed to laminates and prepregs made from the varnish compositions of this invention. The varnish compositions of this invention produce prepregs and laminates that possess excellent thermal and mechanical performance and especially excellent peel strengths.
(2) Description of the Art
There is a laminate phenomenon known as “pad cratering” in which a chip associated with a printed circuit board laminates can become dislodged. Pad cratering is a mechanically induced fracture in the resin between copper foil and outermost layer of fiberglass of a printed circuit board but which may be within the resin or at the resin to glass interface. The pad remains connected to the component (usually a Ball Grid Array, BGA) and leaves a “crater” on the surface of the printed circuit board. Pad cratering is believed to be caused by an accumulation of mechanical stress between the printed circuit board resin and copper. Thus, there is a need for prepregs and laminates used in printed circuit boards that reduce the propensity for the circuit boards to suffer from pad cratering.